| Brassica napus was sensitive to phosphorus deficiency however showed abundance genotypic differences. According to previous large-scaled screening, this research defined a P efficient cultivar 97081 and an inefficient cultivar 97009 of napus under both pot culture and field experiment. Further research on P efficient mechanism in terms with nutritional physiology and genetic behavior were carried out. The main results are as follows:1. By three turns of screening on the favorite P supply concentration for study on P genotypic difference in seedling stage was defined as 5 mol/L for the first time. Under solution culture in seedling stage, P efficient cultivar 97081 has longer main root and more active proliferation of lateral root under P deficiency. Whatever inefficient 97009 have slowed down the growth of lateral roots. 97081 got less affected on P accumulation in both root and top and distribution ratio of top to root to make more tactical use of P.2. Collection and indentification of root exudate on 97081 and 97009 were arranged. It was found that citrate, tartaric acid (malate) and oxalate exudation increased as adaption to P deficiency.3. Digital root parameters for Brassica napus come out through scanning for the first time. Under sandy culture in root box and nutritional paper culture, the differences of two-dimensional root architecture between 97009 and 97081 were observed directly, Results showed that total length, volume, surfacial area, diameter of napus root decreased to various extent with the lowering of P supply. Root secondary differentiation was refrained. The relative value of each root parameter for 97081 was 2-3 folds of that for 97009. Dividing the nutritional paper into four layers to study the change of root architecture on each layer, the characteristics of root gravitropism phenomenon, which were induced by P deficiency, were found out.4. In seedling stage, P nutrition has impacted on uptake and utilization of N, K, Ca, Mg, Fe, Mn, Cu, Zn to some extent. P deficiency restricted the absorption of N and K. For the reason of biomass effect, concentrition of N increased but K decreased. 97081 varied in a smaller scale on N and K. Ca content increased but Mg changed less under P deficiency. Efficient cultivar could absorb more Ca and make effort to keep some balance between root and top. It seems that Mg uptake and transport has no relation with P efficiency. In a total, P had improved uptake and utilization of Fe, Mn, Cu, Zn, but there are some special P level for each nutrients.5. Nutrients acquisition and utilization of 97009, 97081 and their reciprocal cross FI and RFI under P deficiency were studied for the first time. P minus resulted in decreasing of dry weight and P accumulation in flowering stage, silique stage and maturity stage. What's more, the effect accumulated all through the growth history. The high efficiency of 97081 realized through economic and rational regulation on limited P. Heterosis appeared both in FI and RFI under P stress. In different growth stage for napus. Heredity systems participating in P regulation were pretty complicated and changeable.6. Comparing FI to RFI, we found that genes that controlled seed yield, pod number per plant and plant height mainly existed in nucleus. Composite genetic analysis with four generations including P1, P2,F1, F2 showed that: plant height, seed yield and effective pot number was under control of 2 major gene plus multi-gene; No epistatic effect existed between the major gene and the multi-gene for plant height, while for seed yield and pot number, major genes and multi-gene has extensive additive effect, dominance effect and epistatic effect. The heritability of majorgenes and multi-genes for yield reached 36.9% and 56.8%, respectively. The heritability of major genes for pot number and plant height are 74.8% and 61.6%, respectively.7. The first genetic population especially for location of P efficient gene was constructed. Relative values were utilized to analyze geneti...
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